1. Field of the Invention
The present invention relates to a cutting fluid tank used for a machine tool such as a machining center and a turning machine.
In this specification, by “front” is meant an upper side in FIGS. 1 to 11, by “rear” is meant a lower side in FIGS. 1 to 11, and by “left and right” is meant the left and the right in FIGS. 1 to 11.
2. Description of the Background Art
For example, in a machine tool configured to perform a cutting work such as a machining center and a turning machine, cutting fluid is generally used for a purpose of lubrication and cooling of tools and discharge of chips.
The cutting fluid discharged toward a work chamber of the machine tool by a cutting fluid supply pump is discharged to outside the work chamber together with chips scraped out from the work. The discharged cutting fluid flows into a tank body of a cutting fluid tank and stores temporarily after the chips mixed therein have been separated and removed by a chip conveyor or a filter, and is supplied therefrom to the work chamber again by the cutting fluid supply pump. However, the chips mixed in the cutting fluid cannot be separated and removed by 100% depending on the chip conveyor or the filter, and some quantity of chips flow into the tank body of the cutting fluid tank together with the cutting fluid. However, if the chips entered the tank body are sucked into devices such as the cutting fluid supply pump, the devices may be damaged or may break down.
In addition, the chips flowed together with the cutting fluid are gradually accumulated in the tank body, whereby an effective capacity of the tank body, that is, a capacity for storing the cutting fluid itself is reduced. Therefore, when a large quantity of the cutting fluid is supplied toward the work chamber, a problem of exhaustion of the cutting fluid in the interior of the tank body may arise.
In addition, the chips are settled and accumulated on a bottom portion of the tank body, the state and the quantity of accumulation are difficult to figure out at first glance and a lot of time and effort are required for removing the accumulated chips.
Accordingly, installing a chip separating apparatus such as a centrifuge or a magnet separator in a predetermined position in the interior of the tank body and separating and removing the chips from the cutting fluid are performed.
However, the chips contained in the cutting fluid are spread over the entire area of the tank body, and is settled and accumulated on the bottom portion thereof. Therefore, even though an attempt is made to collect the chips by the chip separating apparatus, only part of the chips existing in a peripheral area of the apparatus. Therefore, the chips accumulated in other areas in the tank body cannot be collected.
If a flow of the cutting fluid in the interior of the tank body is fast, since the chips mixed in the cutting fluid move with the flow of the cutting fluid, accumulation of the chips on the bottom portion of the tank body may be prevented or alleviated. However, since the quantity of the cutting fluid flowing in the tank body varies in accordance with the quantity of the cutting fluid required for machining of the work, there are cases where a flow rate is not stable and becomes slow or where the flow is stopped.
In addition, the tank body of the cutting fluid tank is required to secure a maximum capacity with respect to an installation space, and in addition, the devices such as the chip conveyor are disposed in many cases, a structure or a shape is subject to various restraints. Therefore, a narrow portion which is complex and indented portions are formed in the interior of the tank body. Consequently, there arises a problem that the cutting fluid containing the chips stays in such portions and thus the chips are accumulated on the bottom portion.
The problem described above will be described specifically. In the cutting fluid tank, the cutting fluid containing the chips flows as a whole from an inflow position into the interior of the tank body toward a cutting fluid supply device for suppling the cutting fluid to a work portion of the machine tool. However, due to the structure of the interior of the tank body, there may arise points where the flowing velocity is high and points where the flowing velocity is low. Depending on the structure of the interior of the tank body, a plurality of flow channels may be formed into a branched manner from the inflow position toward the cutting fluid supply device. In such a case as well, an average flowing velocity of the cutting fluid is lowered in the tank body as a whole, and thus the state of being susceptible to accumulation of the chips occurs.
FIG. 10 illustrates an example of the cutting fluid tank of the related art.
An illustrated cutting fluid tank (101) is provided with a tank body (2) having a rather laterally elongated box-shape when in plan view.
A chip conveyor (3) elongated in a fore-and-aft direction is installed at a center portion in the interior of the tank body (2). The chip conveyor (3) is arranged below the work chamber of the machine tool, which is not illustrated.
Cutting fluid discharged from the work chamber and chips mixed therein flow into the interior of the tank body (2) from flow-out ports (31) opening at a rear end portion of both left and right side surfaces of the chip conveyor (3) after part of the chips have been separated and removed in the chip conveyor (3).
In the interior of the tank body (2), a right partitioning wall (25) extending in the fore-and-aft direction so as to partition a portion between the chip conveyor (3) and a right side wall (21) into left and right two parts and a left partitioning wall (26) extending in the fore-and-aft direction so as to partition a portion between the chip conveyor (3) and a left side wall (22) into left and right two parts.
Spaces are formed between a front end of the right partitioning wall (25) and a front side wall (23) and between a rear end of the right partitioning wall (25) and a rear side wall (24). A space is also formed between a front end of the left partitioning wall (26) and the front side wall (23). A rear end of the left partitioning wall (22) is connected to the rear side wall (24).
With the configuration described above, the interior of the tank body (2) is partitioned into a right inner area (2a) between the chip conveyor (3) and the right partitioning wall (25), a right outer area (2b) between the right partitioning wall (25) and the right side wall (21), a left inner area (2c) between the chip conveyor (3) and the left partitioning wall (26), and a left outer area (2d) between the left partitioning wall (26) and the left side wall (22), and front ends of the right inner area (2a), the right outer area (2b), the left inner area (2c), and the left outer area (2d) communicate with each other via a front area (2e) along the front side wall (23), and rear ends of the right inner area (2a), the right outer area (2b), and the left inner area (2c) communicate with each other via a rear area (2f) along the rear side wall (24).
A cutting fluid supply pump (4) configured to pump up cutting fluid in the interior of the tank body (2) and feed the cutting fluid to the work chamber of the machine tool is provided at a rear end portion of the left outer area (2d) in the interior of the tank body (2).
A chip separating apparatus (51) composed of a centrifuge, a magnet separator, or the like and a filter (52) are provided in the left outer area (2d) in the interior of the tank body (2) in proximity to the cutting fluid supply pump (4) on a front side (upstream side) thereof.
In the cutting fluid tank (101) described above, cutting fluid containing the chips flowed into the interior of the tank body (2) from left and right flow-out ports (31) of the chip conveyor (3) flows toward the cutting fluid supply pump (4). However, major part thereof flows through the right inner area (2a), the left inner area (2c), the front area (2e), and the left outer area (2d) as indicated by thick lines (C) with an arrow in FIG. 10. Therefore, since the flow velocity of the cutting fluid containing the chips may become extremely slow or may even be held up specifically in the rear area (2f) or in the right outer area (2b), chips (T) tend to accumulate on the bottom portion.
FIG. 11 illustrates other example of the cutting fluid tank of the related art.
In a cutting fluid tank (102) of FIG. 11, a flow channel of cutting fluid containing chips is formed along a one corner portion in a tank body (20). Specifically, a right partitioning wall (203) parallel to a right side wall (201) and a rear partitioning wall (204) parallel to a rear side wall (202) are provided so as to be orthogonal to each other in a right rear corner portion where the right side wall (201) and the rear side wall (202) intersects in the interior of the tank body (20), so that the flow channel bent at a right angle by these four walls (201), (202), (203), and (204) is formed.
In the flow channel described above, since a flow (C) of the cutting fluid changes the direction significantly, a point where the flowing velocity is partly low tends to arise. In other words, at a corner portion between the right side wall (201) and the rear side wall (202) and at a portion along the right partitioning wall (203), the flow of the cutting fluid tends to be held, so that the chips may accumulate on the bottom portion of such a point.
In the related art, several devices configured to prevent the chips from accumulating in the tank body of the cutting fluid tank are proposed.
For example, a cutting fluid tank described in JP-UM-A-6-42045 includes in a tank body: a central separating plate configured to partition the interior thereof into a front part and a rear part, a chip trapping pocket located at one corner portion, and two front and rear movable plates movable along both sides of the central separating plate along the central separating plate. Each of the movable plate includes a nozzle configured to eject cutting fluid so as to form a circulating flow of the cutting fluid in the interior of the tank body, and a scraping plate configured to scrape chips accumulated on a bottom portion of the tank body.
JP-UM-A-4-42350 discloses a cutting fluid tank configured to eject the cutting fluid pumped up from the interior of the tank body through the nozzle so as to run along a wall surface of the tank body to form an eddy current in cutting fluid in the interior of the tank body, so that chips are prevented from accumulating on a bottom portion of the tank body. JP-UM-A-7-7855 discloses a cutting fluid tank having the same configuration as JP-UM-A-4-42350. However, in the cutting fluid tank of this disclosure, chips collected at a center portion of a tank body by an eddy current are pumped up with a pump with cutting fluid, and causes the pumped cutting fluid containing the chips to pass through a filter and to be returned again to the tank body.
In JP-A-2004-114221 and JP-A-2-106248, installing a screw for stirring cutting fluid in an interior of a tank body of a cutting fluid tank to prevent chips from accumulating on a bottom portion of the bank body is disclosed.